The helminthic diseases known collectively as filariasis, affect both humans and animals and are caused by a nematode parasite. The adult filarial worms (macrofilariae) live in the lymphatic system, tissues and body cavities of the vertebrate host. The female produces partially embryonated eggs which contain embryos that uncoil and become microfilariae. An effective drug should cause the death of either the macro- or the microfilariae and, preferably, both forms. Chemotherapeutic agents that can effectively damage or destroy either the microfilarial or the adult stages of filarial worms that infect man have been available for several decades. However, treatment remains problematic because the drugs cause adverse affects to the host and they inhibit or destroy either the adult worms or the microfilariae, but not both.
This invention utilizes heterocyclic and aromatic thiosemicarbazones to eliminate macro- and/or microfilariae. The most effective of the series is filarizone (Code No. BK49685 in the Table) which completely destroys both macro- and microfilarae of Acanthocheilonoma viteae and macrofilariae of Brugia pahagi at therapeutic dose levels without causing apparent toxicity to the host.